Understanding Electrical Grounding and How It Works
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why it's important to understand household wiring
Grounding is a principle of electricity often mentioned in wiring projects but can be confusing to homeowners and DIYers. To understand the importance of electrical grounding in a home wiring system, you'll need to understand the nature of electrical eenergy flow.
What Is Electrical Grounding?
Grounding offers excess electricity the safest, most effective route from an appliance back to the ground by way of an electrical panel. Electrical grounding is a backup pathway, only used if there are faults in the wiring system.
Grounding Basics
The electrical current in your home's wiring system carries a flow of electrons through its metal circuit wires. This polarized current comes in two forms: a negative and a positive charge.
The negative half of the charge is the "hot" current, which you'll typically see carried by black wires in your home. White neutral wires carry a positive charge. Both sets of wires enter your home through the utility's main service wires, running through your electrical service panel and side-by-side through every circuit in your home.
Electricity seeks to return its electrons to "ground"—discharging negative energy and returning to equilibrium—which would normally happen through the neutral wires in an electrical system. But if there are any breakdowns or short circuits along the pathway, the hot current may stray and try to take a shorter path to ground through other materials, such as metal or wood framing, metal pipes, or insulation. This is how most electrical fires and shocks start.
Built-In Protection
Your home's wiring system will also include other safety devices to help minimize the risks of shock and fires. Circuit breakers or fuse boxes are in place to protect and control each circuit. These serve two functions: protecting the wires against overheating if they are ever overloaded, and tripping or "blowing" to instantly stop the flow of current when they sense short circuits.
The metal plumbing pipes in your home may also be connected to the grounding pathway, and are typically protected by a grounding wire clamped to a metal water pipe near your water heater or where the public water line enters your home.
Appliance Grounding
Not only does your home wiring system have a grounding system for safety but many plug-in appliances and devices also do. High-power appliances such as power tools and vacuums are much safer when they have a third prong on the plug, which is shaped to fit the round grounding slot on an outlet receptacle.
The presence of this third prong shows an appliance has a grounding system, and it's essential to only plug these into grounded outlets.